Sibelius - Sibelius is a virtual score creation tool which allows composers to easily create new piano scores, developed by Avid.
iHandy Carpenter - An handy carpenter tool kit right on your device! There are 5 tools in this Carpenter tool kit:
Guitar Pro 7 - Create, play and share your tabs
Angle Finder™ - Angle Finder™, now rebranded to Protractor+, is an app that offers a handy protractor tool on your phone.
LilyPond - GNU LilyPond is a computer program for music engraving.
Pocket Ruler AR - Pocket Ruler AR is a pocket ruler app that lets you measure objects and distances with your phone.